1. Field of the Invention
The present invention relates to a color video signal processing apparatus which processes a color video signal and, more particularly, to a color video signal processing apparatus which performs analog-to-digital conversion (to be referred to as A/D conversion hereinafter) for each component signal included in the color video signal.
2. Description of the Prior Art
Conventionally, a television signal is sampled at points a, b, c, . . . on lines 2 along a vertical direction a of an image plane 1, as shown in FIG. 1. Thereafter, the obtained signal is A/D converted.
FIG. 2 shows a conventional processing circuit for A/D conversion. In the drawing, reference numerals 3, 4 and 5, respectively, denote R, G and B signals which are supplied into the circuit. These signals 3, 4 and 5 are A/D converted by A/D converters 6, 7 and 8 to obtain digital data 9, 10 and 11, respectively. A horizontal sync signal 12 is supplied into a sampling pulse generator 13. The generator 13 then generates a sampling pulse 14 to control the A/D converters 6, 7 and 8.
In this case, since a video signal of high frequency is sampled, the aperture for sampling must be set small. Therefore, even if a sampling period and a horizontal scanning period are the same, an A/D converter of high speed is required. Generally, such an A/D converter of high speed is so expensive that, if a system of this type requires three converters, the system is also expensive.